Apparatus for contacting gases with solid fluent materials



R. NEWTON 2,490,828 APPARATUS CONTACTING GASES WITH SOLID FLUENT MATERIALS Filed Feb. 5, 1945 Dec. 13; 1949 INVENTOR By ROGER h- NEWTON ATTORNfY Patented Dec. 13, 1949 APPARATUS FORYCONTACTING GASES wrrn soLm FLUENT MATERIALS Roger H. Newton, Bowling Green, Pa., assignor to I Houdry Process Corporation, Wilmington, Del.,

- a corporation of Delaware Application February 5, 1945, Serial No. 576,301. 2 Claims. -(o1. 23-288) The present application relates to an invention claimed in its broader'aspects in my copending in which the material application, Serial No. 576,306 flled February 5,

1945, which latter application is in part a continuation of my copending application, Serial No; 426,294, filed January 10, 1942, now abandoned.

In modern industrial operations a fluent body of solid material is frequently discharged by gravity flow from a container through a constricted outlet in the bottom of the container.

In many instances it is desired that the fluent solid materials charged at'the topof the container move downwardly through the container at equal rates throughout the transverse section of the container. This is particularly true in instances where it is desired to have all of the material remain in the container for substantially' equal times. It is likewise true in opera tions in which the solid fluent material flows through the container intermittently and it is desired to replace the material in the container with a fresh charge of material, the discharging and charging occurring simultaneously..

In order to obtain equal downward flow throughout the transverse section of the container, the bottom wall of the container has frequently been funnelled to the outlet at an angle greater than the angle of repose of the solid fluent material. Investigation has shown that unfortunately this does not, produce equal downward flow. channelling occurs because the material at the side of the container does not slide down the bottom wall to a sufficiently appreciable extent. The greatest flow occurs in a stream vertically above the outlet. Thus, in a container having a substantially vertical cylindrical wall to which is joined a conical bottom wall inclined at an angle greater than the angle of repose, there is a considerable zone of virtually static solid material adjacent the cylindrical wall.

Objects of the present invention are to provide improved systems for containing a moving body of solid fluent material in which the rate of flow is substantially equal throughout-the body or bed when the material is moving to .andthrough a constricted outlet at the bottom of the container; and to provide improved means for contacting solid fluent materials with fluids, in either gas or liquid state, in which the-solid fluent material moves downwardly through a container and should move at equal linear rates throughout the transverse section of the container. Thus, in a. base exchange system, the zeolite in "granular or other solid fluent form may be introduced at .the top of a tank of substantial elevation and move downwardly as a body therethrough. A solution of material to be contacted with the zeolite is introduced into the tank. Thezeolite is charged at the top of the tank and discharged from a constricted opening at the bottom of the tank after base exchange.

This invention further is applicable in the catalytic fleld. Thus, the purpose may be to heat treat the catalyst, in which event the catalyst is charged to the top of the heat treater and discharged from a restricted opening in the bottom thereof. A treating gas may be introduced into direct contact with the catalyst or a heated gas may be employed in indirect heat exchange relation therewith. In order to effect uniform treating it is of substantial importance that all residence times, wherefore it is important that the rate of flow downwardly in the treater be.

equal throughout the transverse section. In

catalytic processing, as for example, in catalytic cracking, wherein a body of catalyst flows downwardly through the catalyst case in direct contact withthe oil vapors to be cracked or through the regenerator in direct contact with air it is of considerable importance that the rate of flow be uniform throughout the case. Otherwise some portions of the catalyst will leave the case before suflicient cracking has been effected in contact therewith for regeneration to be necessary, while other catalyst will have far surpassed its utility without regeneration. In connection with regeneration unequal fiow results in non-uniform regeneration.

In accordance withthe present invention flow restricting means is positioned in the lower portion of a container through which container a solid fluent material flows by gravity, and thence out of a constricted opening in the bottom thereof. The flow restricting means restricts flow to the greatest extent adjacent the outlet opening. The restriction to flow decreases with increasing distance from the outlet. The flow restricting means is so positioned that the angle to the horizontal formedby a line from the outlet opening to the portion of v the restricting means most distant from the outlet opening is greater than the angle of repose. Preferably the flow restricting means is positioned at an angle at least as great as the angle of repose of the material. The portion of the bottom wall of the container which is below the flow restricting means may be either horizontal or at an angle. By positioning the bottom wall at an angle directed downwardly tooo ward the outlet, all. the material flowing through the container eventually moves out the outlet. In the case of a horizontal bottom wall an inclined static bed of material reposes on the wall, all the material flowing through the container moving over this bed to the outlet.

' In this specification and in the subjoined claims the flow restricting means is variously referred to as a grid, a grate, and a baflie, which terms are used herein as synonymous.

It is frequently necessary to remove from a fluent body of solid particles, material which remains from a previous operation. This can be accomplished by purging with a gas. When extended contact with the purging gas is harmful to the solid particles, the purging gas should be removed as soon as purging is complete and further exposure thus avoided. Another object of this invention is to provide improved systems for serial contact of a moving bed of solid fluent material with a plurality of gaseous media.

In this respect, the invention is particularly useful in the field of catalytic processing of hydrocarbon material. A moving bed of solid fluent catalyst which has been used for the cracking of hydrocarbon vapors contains gaseous hydrocarbons and the catalyst is coated with a heavy coky deposit. It is preferable to remove these gaseous hydrocarbons before regeneration with an oxidizing gas to prevent the hazard of an explosion. Furthermore, if the vaporizable portions of the heavy coky deposit are stripped from catalyst prior to regeneration, the amount of such regeneration is reduced since there is less of the deposit to be burned oil. This can be done by purging with a nonoxidizing gas. Steam has be performed by using the flow restricting means been found to be very eflicacious but prolonged exposure to such an agent is known to be deleterious to the catalyst. In the present invention, purging is accomplished by steam in a zone where the velocity of the bed of fluent catalyst is increased, whereby the contact time of steam with the catalyst may be considerably diminished and whereby better control of the purging operation is possible. The effect of steam on the catalyst may be further reduced by dilution with an inert gas such as flue gas.

This specification has previously discussed discharge of a moving bed of solid fluent material through a constricted outlet and the effect of a flow restricting means above such an outlet. Purging may be accomplished either in an elongated constricted outlet, which by its very nature produces a zone of increased velocity or in the flow restricting means which may provide a zone of appreciable thickness for that purpose. ious modes of utilizing this invention may be employed. The purge gas may be introduced in an elongated constricted outlet, passed upwardly through the downwardly flowing stream of solid fluent catalyst, mingled with the hydrocarbon vapors in the catalyst chamber, passed upwardly through the catalyst chamber and be discharged from the top thereof. If it is desired to keep the purging medium separate from the hydrocarbon vapors, the purging gas may be introduced at a point in the zone of increased velocity of the solid fluent catalyst, passed upwardly through the-downwardly flowing stream of solid fluent catalyst and be disengaged at a point still within the zone of increased velocity. In the latter operation the apparatus is designed so that, at the disengaging zone, the tendency of the purge gas to flow upwardly into the treating chamber is substantially balanced by the tendency of the Varhydrocarbon vapors to flow downwardly from the cracking chamber. Both of these operations may tion of anapparatus embodying this invention and shows a, chamber or container with flow restricting or impeding means positioned therein;

Figure 2 is a horizontal section on line IIII in Figure l and shows details of the construction of the flow restricting means;

Figure 3 is a vertical section of the lower portion of a chamber showing different forms both of the flowing restricting means and of the bottom wall of the chamber.

The present invention isadapted to the cracking of hydrocarbon vapors by contact with a moving bed of solid granular catalyst, and is described in connection therewith. The cracking case, chamber, or container has a substantially vertical cylindrical wall- I. The bottom wall 2 and top wall 3 are joined to wall I. Walls 2 and 3 are welding heads which have the advantage of being standard pieces of engineering equipment and adapted for use when maintaining a pressure in the cracking chamber. However, the top or bottom walls may be in other forms, such as horizontal or conical. The catalyst is charged from a hopper (not shown) to pipe 4 and is deflected and distributed byconical deflector 5 which is positioned in the upper portion of the chamber and laterally spaced therefrom to provide an annular peripheral inleti. The solid fluent catalyst moves by gravity. as a bed to flow restricting means 'Lpositioned in the lower portion Of the chamber.

The flow restricting means is conically shaped with the apex ofthe cone disposed downwardly. Means is positioned above the outlet and is inclined upwardly and outwardly so that the cone forms an angle with the horizontal which is greater than the angle of repose of the solid fluent material. The periphery 20 of the flow restricting means I 'is vicinal to the cylindrical wall i; The flow restricting means 1 has holes II which provide passage for the solid fluent material. The center to center spacing of holes 2i decrease as the distance from the apex of the cone increases. The closed or web area 22 and hence the restriction to flow increases with increasing proximity to the outlet. The holes 2! may be of any desired size or shape and may increase in either size or frequency of occurrence with increasing lateral spacing from the axis of the cylindrical wall. Thus in means I, the ratio of passableor free area to closed, solid, or obstructed area increases as the distance from the outlet increases and thereby produces substantially equal flow in all the annular areas of the bed above it.

In Figural, after passage through the flow restricting means I, the catalyst flows to and through a vertically elongated outlet 8 which is provided with a chamber 9 for the introduction of a purging gas and a chamber ID for the distom wall 2 and the flow restricting means '1,

whereby the position of the flow restricting means is permanently fixed- Pipes I2 have ports I3 for the distribution of .hydrocarbon vapors in the catalyst bed, and thus serve the dual purpose of introducing the hydrocarbon vapors and supporting the flow restricting means 1. Pipes I4 are welded or suitably secured to both the top welding head 3 and the conical deflector 5, and serve to fix the position of said conical deflector 5. The open ends of pipes I4 communicate throughconical deflector 5 whereby pipes I4 serve the dual purpose of removing the cracked hydrocarbon vapors and of supporting the conical deflector 5. Steam, flue gas, or a combination of these is introduced through pipe I5 into chamber 9 and flows upwardly to chamber I0, countercurrent to the stream of fluent catalyst, and thence out pipe IS. The direction of the purging gas with respect to the fluent stream of catalyst may be reversed, in which event the purging gas is introduced in chamber II] and disengaged in chamber 9.

In use with valve II closed, the catalyst is charged through pipe 4 until the level of the bed reaches conical deflector 5. The surface of the bed will b disposed at the angle of repose as shown by broken lines I'I. Valve II is then opened and the rate of discharge and of charge of the fluent catalyst is regulated to produce the desired rate of flow through the chamber. The fluent catalyst will travel downwardly through the bed at substantially equal rates while the hydrocarbon vapors introduced through pipes I2 travel upwardly through the bed. The cracked hydrocarbon gases are removed from. the apparatus through pipes I4 and thereafter suitably processed. The direction of flow of the hydrocarbon vapors may be reversed. The fluent catalyst, all of which has had the same residence time in the cracking zone because of the operation of the flow restricting means 1, passes through the flow restricting means I and thence to the constricted outlet 8. A purging gas introduced through pipe I5 passes upwardly through the downwardly flowing fluent catalyst and removes therei'rom gaseous hydrocarbons and the vaporizable portions of the coky deposit thereon. Most of the purging gas and purged products pass out through pipe I6, but a small portion moves upwardly, countercurrent to the catalyst, into the cracking chamber thereby sealing ofl the hydrocarbon vapors therein from further downward flow.

Figure 3 shows an embodiment of the invention in which the flow restricting means is composed of solid rings 25. These rings vary in diameter, and are spaced from each other at distances which increase as the distance from the outlet increases.- Rods 26 are joined to the various rings and mainrates in the transverse section of the bed above the flow restricting means or grate, and flow to and through the grate and will flow into the passage 28 between the grate and the inclined bottom wall 21 and thence to the outlet 8. Under such conditions there is no substantial amount of the solid fluent material which remains static in the chamber.

The angle of repose of any material is readily measurable. In general, angles of repose of solid fluent materials lie within the range of about 25 to about 60.

I claim as my invention:

1. In apparatus of the class described, a chamber having a substantially vertical cylindrical wall and having a conical bottom wall with the apex of said cone disposed downwardly, said chamber having an outlet at the apex of said bottom wall, a conical deflector with its apex upwardly disposed, the peripheral portion of said deflector being located in the upper portion of said chamber and within and spaced from the substantially vertical cylindrical wall, whereby to provide an annular peripheral inlet to said chamber, and a conical grid positioned with its apex downward and located in the lower portion of said chamber in spaced relation with respect to said bottom wall, said grid being provided with passages therethrough, the ratio of passable area to impassable area of said grid increasing with increasing distance from the apex of said conical grid, and means for controlling rate of discharge through said outlet, whereby a solid fluent material charged through said inlet enters the chamber peripherally, forms a bed in said chamber, distributes uniformly over the surface of said bed, flows downwardly at equal rates to said grid, flows through and below said grid, and flows along said bottom wall to and through said outlet and flow controlling means.

2. In apparatus of the class described, a chamber having a substantially vertical cylindrical wall and having a conical bottom wall with the apex of said cone disposed downwardly, said chamber having an outlet at the apex of said bottom wall,

I a conical and positioned with its apex downwardly and located in the lower portion of said chamber in spaced relation with respect to said bottom wall, said grid being provided with passages therethrough, the ratio of passable area to impassable area of .said grid increasing with increasing distance from the apex of said conical grid, and means for controlling the rate of discharge through said outlet, whereby a solid fluent material introduced into said chamber, after distribution over the upper surface of a bed of the fluent material, flows downwardly at equal rates to said grid, flows through and below said grid,

and flows along said bottom wall to and through said outlet and flow controlling means.

ROGER H. NEWTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,617,960 M-uller Feb. 15, 1927 FOREIGN PATENTS Number Country Date 703.784 France Feb. 10. 1931 

